In an LTE system, multiple users share a system resource in an “orthogonal” manner. “Orthogonal” herein means that one system resource block (for example, an RE) can be allocated at most to only one user (or virtual user) for use. Therefore, a manner in which different users occupy a frequency resource is “orthogonal”. This orthogonal resource allocation manner has its practical aspect, but is far from being optimal in terms of spectral efficiency and a channel capacity. Recently, a “non-orthogonal”-type air interface access manner gradually becomes a hot topic among international scholars, and is likely to become one of focused topics of a next-generation cellular communications technology (for example, 5G, fifth generation communications technology). “Non-orthogonal” means that multiple users may share a system resource such as a frequency spectrum in a non-orthogonal manner.
Specifically, according to the existing non-orthogonal air interface access, multiple codewords are allowed to be superposed on one system resource block for transmission. The codewords are superposed in a manner similar to an LDPC (Low Density Parity Check Code, low density parity check code) sparse matrix, and a decoder is used at a receive end to decode information of the multiple codewords to restore original information.
However, a prior-art decoding method is relatively complex and has a relatively high requirement for hardware.